Spark plug construction



May 15, 1945. J. J. ROSE SPARK PLUG CONSTRUCTION Filed Sept. 18, 1943 SJIII EE 3/1 H/IV/III-E FIG.4-

INVENTOR Q/OHN R0 SE 6,12 A TTORNE YS Patented May 15, 1945 2,375,822

UNITED STATES PATENT OFFICE SPARK PLUG CONSTRUCTION John J. Rose,Dayton, Ohio Application September 18, 1943, Serial No. 502,888 8 4Claims. (01.123-169) (Granted under the act of March 3, 1883, as

amended April 30, 1928; 370 O. G. 757) The invention described hereinmay be manufactured and used by or for the Government for governmentalpurposes, without the payment to me of any royalty thereon. with ahexagonal portion 6 to which a tightening This invention relates toimprovements in wrench is applied and a crimped over portion 8 sparkplug construction whereby it becomes poswhich locks the insulator 2within the body I. In sible to modify a standard automotive type sparkorder to keep the cost of manufacture low, the plug construction torender the same applicable body 3 is turned from hexagon bar stockwluch,to the construction of shielded or unshielded of course, leaves thegasket seat portion 5 w1th a spark plugs for aircraft ngine ignition andthere- It) hexagonal pgriphery. 2211611 plugstlof tll ns type by effecta considerable saving in cost. are emp oye on aircra engines e c ampmgThe plug bodies of aircraft type spark plugs pressure exerted by theseat 5 on the soft gasket differ from those employed in automotivepracring 1 causes indentations at the corners of the tice mainly in thataircraft plug bodies are formed hexagonal sides of the seat 5, and afterthe plug with a larger diameter gasket seat to effect a has been e d areplaced a few es the proper seal to prevent leakage at the highercomgasket becomes chewed and distorted and will no pression pressuresemployed in aircraft engine lonier3 prlolpefily sgal, reqfi l ie gwg b fthe cylinders. Since it is not possible to form the g 6, 0 1S equen y o00 6 y plug body directly from hexagonal bar sto k t chanics. If thegasket section? were turned to give the requisite gasket seat diameterWithout a Ci ular form, the diameter ofth gasket W0l1 also increasingthe dimensions of the hexagonal be inadequate tic propgerily distribulte1the sealing portion of the plug body where a wrench is appressure, d 8gas 6 Seat W011 (1 d 0 plied beyond standard dimensionsJt has been thedent 2% gasket; and'ciif thlelbody of i P Were practice to form th lugbodies of round b forme y urning an m1 mg so as 0 ive a cirstock andthen mill .the hexagonal portions of Gular gasket seat of the requisitediameter, the the plug body, which materially increases th cost ofmanufacture would be greatly increased cost of manufacture, andproduction would be limited due to increased In accordance with thepresent invention and machining timeconstituting its primary object, thespark plug In accordance with the invention, the problem body is formed1mm hexago al bar Stock in a of forming a gasket seat which W111 notdamage manner similar to the formation of an automothe plug gasket andst 111 allow the P y t tive plug bgdy but isdso lmachlgnid that aseparate 2:; 523 32 2 8 i l igrsririlgiggon baif" stock (21 a scgew ringmay e presse s run razed, or welded mpne 01min gure m thereon to givethe necessary gasket seat diamewhlsh f ii f pgrlghery oftthe i t 88:17ter. t 35 par ion 0 e put; 0 y 3 is urne own 0 The features of noveltyof the invention will be form? Shoulder onto which is p ess d anennuiurther apparent by reference to the detailed deg, or washer whlch tface scription hereinafter given and to the appended s f i g i 2,2 gg if portion of drawing, in which ns ruc ion gives a t Figure 1 illustratesa conventional automotive 2 55;: fig ifi 53 13 and i circuiarflclontolirype of spark plug; S al y amage 0 e sea t Figure 2 illustrates one formof a plug similar gi ggfiifi g fig gi 2 1 3 2 3 an engine 0 t at ofFigure 1, modified in accordance with 6 any the invention; berlof time;without requiring replacement of the a fragmentary w of portion of z iggri il l strates to an enlarged scale a modi gz i 8 g g fiifif ifurther fled construction in which the projecting portion Figure 4 is aView Similar to Figure 3 muscrab of the gasket seat 5 1S turned on flushth t plug body and an annular ring 10a placed theremg another Vamtlon ofthe on' with a light push fit so that he r t f In the appended drawing,Figure 1 illustrates f the ring ma is flush with the of i a aFonventiona] spark plug which may be seat 5. The rear face of theannular ring lfla is tamed at low cost, havingthe insulator 2mountchamfered as at l i and this chamfer is filled with ed ma metalbody having a threaded portion brazing metal 12 which may be applied inpaste 4 which is screwed into the engine spark plug form and melted in ahydrogen atmospherefuraperture, and having a hexagonal portion 5 whichserves as a gasket seat for a conventional gasket ring of soft copper l.

The body 3 is provided nace at the same time the plug body electrodesare brazed in place. This construction has the same advantages as abovedescribed with reference to Figure 2.

Figure 4 illustrates a further modification which is similar to thedevice of Figure 2 except that the projecting portions of the gasketseat 5 are left oil? and the annular ring lflb is made of a suflicientlength to abut the hexagonal portion 6 of the plug body. The ring 10bmay be pressed or shrunk on the plug body 3 and also may be brazed inthe manner illustrated in Figure 3-.

While the invention is shown as applied to unshielded spark plugs, theinvention is similarly applicable to shielded spark plugshaving atubular shielding extension formed as an integral part of the plug bodyand this will allow the shielded plug body to be made from hexagon barstock as distinct from the present procedure of forming the plug bodyfrom round bar stock and milling the hexagonshape for application ofthewrench.

While preferred forms. of the invention have been illustrated anddescribed, other modifications and variations thereofwill becomeapparent tothose skilled in the art as coming within the scope oi theinvention as: defined inthe appended claims.

I claim:

1 In aspark plug construction of the character wherein the plug body ismade from hexagonal metal bar-stock and has a hexagonal portion for theapplication of a tightening wrench and a portion joining said hexagonalportion having an endfaoe forminga sealing gasket'seat: the

improvement which comprises providing a, circular shoulder on saidgasket seat portion concentric with the axis of the plug body and anannular ring secured on said shoulder and extending radially beyond saidgasket seat portion, an end face of said ring forming a continuation ofsaid gasket seat face.

2. In a spark plug construction of. the character wherein the hollowplug body is made of hexagonal metal bar stock and provided with athreaded portion for insertion in an engine cylinder, ahexagon portionfor application of a wrench and a third portion intermediate said firstnamed portions, said third portion having a radially extendingv end.face forming a gasket seat: the improvement which comprises securing anannular ringon said plug body portion concentric with the longitudinalaxis of said plug body, said ring having, an outside diameter greaterthan the diameter of said third portion and having an end face: forming:a continuation of the gasket seat face of said plug body third; portion.

Bl The, structure'as claimed inclaim 2, in which the plug body thirdportion is cylindrical, said ring-"being seated on. the said cylindricalportion of the plug body and: an end face of the ring being flushwiththe gasketseat face of the said

